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United States Patent | 5,059,916 |
Johnson | October 22, 1991 |
A gauge circuit for use with a wide angle air core meter display having high linearity and adapted for use with a remote sensing resistor. A constant sense current is provided and its value is moudlated at a frequency that is high with respect to the frequencies associated with offset voltages that occur with a sense resistor that is grounded remotely from the gauge ground. A low duty cycle pulse modulation shape is disclosed for the purpose of minimizing electromagnetic interference radiation.
Inventors: | Johnson; Nick M. (Los Altos, CA) |
Assignee: | National Semiconductor Corporation (Santa Clara, CA) |
Appl. No.: | 462174 |
Filed: | January 8, 1990 |
Current U.S. Class: | 324/713; 324/143 |
Intern'l Class: | G01R 027/02 |
Field of Search: | 324/691,693,713-715,143,146,151 R,154 R,720,128,140 R,141 |
3657640 | Apr., 1972 | Jelinek et al. | 324/693. |
______________________________________ COMPONENT VALUE ______________________________________ Capacitor 23 .047 microfarad Resistor 30 2 k ohms Resistor 31 2 k ohms Resistor 33 5 k ohms (variable) Resistor 34 200 ohms Resistor 37 1 k ohms Resistor 41 15 k ohms Capacitor 42 1 microfarad ______________________________________